K31 Reloading Issues

[Hex1994]

I can't seem to properly reload 7.5x55 Swiss ammo. They always have a rough time extracting from the chamber after being fired, sometimes to the point where I have to mortar the bolt to get it extracted.

I've checked every case, all of them are within standards, primers are still rounded so I don't think its over pressure, I'm starting to worry it might just be the rifle's chamber reacting to the heat of the fired cartridge.

Components:
-Hornady reloading press and die set
-IMR 4064 at 39.5 gr
-Hornady 150 gr FMJ
-PPU Brass
-Federal Large Rifle Primers

[jsanch03]

[pacrat]

Welcome to CalGuns Hex.

In order to get to the root cause we will need more input.

How does your rifle handle factory ammo? Any extraction issues? Or is this only an issue with your own loads?

[BigBronco]

Are you trimming the brass .010" under the max length?.

[TKM]

Go to the home of Swiss Rifle information.

https://www.swissproductsusa.com/faq

[the_tunaman]

Close examination of the cases should tell whether they are hanging up at the base, body or neck.

Any signs of bulging? You didn’t say anything about your loads - try reducing the charge a little if you’re in the upper range and see if that helps.

[SandDiegoDuner]

Take a resized case and color it with a sharpie and chamber that case carefully. Extract the case and see where the marks are at. Remember to color the base of the brass near the primer as well as I believe the bolt rotates as it opens.

[kcheung2]

Which brand of die are you using, and which gun is it? K31, k11, etc?

Although they technically all use 7.5x55 GP11, the chambers are different depending on which gun. In particular, K31 needs a specific K31 die, the RCBS 7.5 Swiss die will approximately match the chamber but that brass will have a very short life.

[Hex1994]

I do apologize as I'm new to this forums system and don't know how to multi-quote properly to answer everyone's questions.

jsanch03: Single stage press and I have only been reloading for about 2 years now. When you say back off 1/8th of a turn do you mean the handle or the die?

pacrat: I have thus far been unable to obtain factory GP11 ammo to provide a good base set of measurements or a control group.

BigBronco: Yes I have been trimming under by about 0.050

the_tunaman: So far all bulging has been around the necked area and a little in the mid section of the shell. Running it through the tends to fix it.
As listed above I'm using 4064 IMR powder at 39.5 grs charge. I'm using a Hornady reloading book.

SandDiegoDuner: Ive done the sharpy trick before, a small amount of scratching along the main body of the casing and the neck but nothing note worthy. Ill give it another go though to double check next time I'm at the range.


kcheung2: As listed above I'm using a Hornady press and Hornady die set. Rifle is a K31.
I have considered using a RCBS die as most forums I've looked through suggest them over the Hornady die sets due to seemingly better sizing.

[kcheung2]

How clean is the chamber? Is the first case you fire relatively easy to extract, and then they get progressively harder as you fire more rounds? Or is extraction tough right from the start, even starting from a cold gun? What you're describing sounds exactly like what many Mosin owners have with all that lacquer coated surplus they use. As the chamber heats up, all that lacquer starts turning goopy and really sticky. I don't think there was any lacquer-coated Swiss ammo but maybe there was.

Your powder charge is on the mild side so I don't think that's it.

At first I thought it was a problem with your die but now I'm not so sure. I still recommend that you get the Redding K31-specific die set (#80235) if your only gun is a K31.

[pacrat]

jsanch03: Single stage press and I have only been reloading for about 2 years now. When you say back off 1/8th of a turn do you mean the handle or the die?

Just a guess, but I believe he meant "further down" as per standard FL die instructions. Not "back off 1/8 turn".

Without having hands on eyes on info. I can only guess. So here we go.

Check your load info against a reputable manual that lists pressure levels for loads. Or maybe you can talk someone here that has the correct software to check it.

You need to be well below the 55,000 psi MAX rating for the 7.5x55. And starting, at start level loads is always best. Then work up slowly.

If loads are well below Max, but experiencing hard extraction issues. I would suggest you do a chamber cast or bore scope the chamber. Both wouldn't hurt.

High pressure, and rough chamber, are the two leading causes of rough extractions. But no two rifles are the same. They all have their individual foibles.

[OpenSightsOnly]

I can't seem to properly reload 7.5x55 Swiss ammo. They always have a rough time extracting from the chamber after being fired, sometimes to the point where I have to mortar the bolt to get it extracted.

I've checked every case, all of them are within standards, primers are still rounded so I don't think its over pressure, I'm starting to worry it might just be the rifle's chamber reacting to the heat of the fired cartridge.

Components:
-Hornady reloading press and die set
-IMR 4064 at 39.5 gr
-Hornady 150 gr FMJ
-PPU Brass
-Federal Large Rifle Primers

If you are re-sizing once-fired brass fired from your rifle, did you measure length of the brass?

If not, use a de-primed 9mm case, insert the once fired, de-primed, and non-FL sized brass into the 9mm case.

Measure the length.

The FL-sized brass should be two thousandths of an inch less than non-fL sized brass that had been fired from your rifle.

Trim to Length is 2.170", based on Sierra reloading manual

[pacrat]

If you are re-sizing once-fired brass fired from your rifle, did you measure length of the brass?

He Isn't

[MarikinaMan]

Like the guys said, are you loading to spec? Do the sized cases pass a case gauge?

If yes, I’d check for over pressure causing the stuck cases by looking at the primer, the case and referencing velocity.

Good luck!

[saki302]

Are you pressing the bullet in far enough? I have to seat 147/150gr bullets in past the cannelure to get them to chamber nicely in my k31.

Maybe yours is touching the rifling, causing a weird pressure spike?

Or.. the chamber is just dirty/sticky.